Gas water heater

ABSTRACT

This invention relates to a gas water heater wherein a diaphragm for opening a gas valve utilizing the water flow is provided in the course of water supply passage to a heat exchanger, the low pressure chamber of said diaphragm is communicated with a low pressure Venturi portion formed by the aid of increasing the flow velocity in the water supply passage, and a control element is proceedably and recedably provided in the Venturi portion to automatically regulate the aperture of the Venturi portion corresponding to the variation of amount of water flow, intended for automation of water amount control and promoting the enlargement of range of adjusting water temperature and simplification of operation.

ilnited States Patet Kawabata et al.

1 Mar. 27, 1973 GAS WATER HEATER [73] Assignee: Matsushita ElectricIndustrial Co.,

Ltd., Osaka, Japan Filed: Oct. 14, 1970 App1.No.: 80,733

Related U.S. Application Data [62] Division of Ser, No. 794,746, Jan.28, 1969, aban- [56] References Cited UNITED STATES PATENTS 2,017,31110/1935 Jacobson ..137/502 Merten ..236/25 Donges et al ..236/25 PrimaryExaminerMeyer Perlin Assistant Examiner--Ronald C. CaposselaAtt0rneyStevens, Davis, Miller & Mosher [57] ABSTRACT This inventionrelates to a gas water heater wherein a diaphragm for opening a gasvalve utilizing the water flow is provided in the course of water supplypassage to a heat exchanger, the low pressure chamber of said diaphragmis communicated with a low pressure Venturi portion formed by the aid ofincreasing the flow velocity in the water supply passage, and a controlelement is proceedably and recedably provided in the Venturi portion toautomatically regulate the aperture of the Venturi portion correspondingto the variation of amount of water flow, intended for automation ofwater amount control and promoting the enlargement of range of adjustingwater temperature and simplification of operation.

3 Claims, 10 Drawing Figures PATENTEUHARZHQH SHEET 1 BF 3 FIG.

N B H H'O H IPyRSH'I ATTORNEY S PATENTEDHARZYIQH SHEET 3 [IF 3 m 1 O w Wn n ow v70 1 Nm NIH U N H/ 00 mm I n H" /b m0 mm UH mm W ATTORNEY S GASWATER HEATER This is a division of U. S. Pat. Application Ser. No.794,746, filed Jan. 28, 1969, now abandoned.

This invention relates to a gas water heater provided with a controllerwhich automatically operates depending on the change of the amount ofwater flow through a hydraulic pressure responding portion that opens orcloses a gas valve, making it possible to obtain water at temperaturesin wide range from high temperature to low temperature merely byregulating the amount of warm water at the supply outlet of warm water.

In general gas water heaters, the regulation of gas supply to the gascombustion portion is usually performed by utilization of the water flowflowing to a heat exchanger. FIG. 8 shows a basic principle of that typeof gas regulation, wherein 1 is a diaphragm operating chamber dividedinto a high pressure chamber 3 and a low pressure chamber 4 by means ofa diaphragm 2, 5 is a valve rod whose one end passes through the lowpressure chamber 4 of said diaphragm operating chamber and whose endportion contacts with one face of the diaphragm 2 and the axial movementof the valve rod 5 opens or closes a gas valve (although this is notshown in the figure), 6 is a water supply pipe to a heat exhanger havinga Venturi portion on the way, 8 and 9 are connecting pipes connecting alarge diameter portion 10 of said Venturi portion 7 and a constrictedportion 11 of Venturi portion 7 to the high pressure chamber 3 of thediaphragm operating chamber and to the low pressure chamber 4 of thediaphragm operating chamber, respectively.

Now, when water flows as shown by the arrowhead in FIG. 8, a pressuredifference represented by Bernoullis theorem is generated between thelarge diameter portion 10 and the constricted portion of the Venturiportion and this pressure difference is transmitted between the highpressure chamber and the low pressure chamber of the diaphragm operatingchamber through connecting pipes 8 and 9. Consequently, the diaphragm 2bends downward in the figure because of this pressure difference andpresses a valve rod 5, thus opening the gas valve. In this case, aconsiderably large amount of force is required to move the gas valve inconsideration of the restoring force of the diaphragm 2 of the restoringforce after closing the gas valve. When the flow rate at Venturi portion7 is small, the constricted portion 11 needs only to reduce in diameterin order to obtain the desired pressure difference. However, if theconstricted portion 11 reduces in diameter, the resistance to flowincreases and the amount of warm water supply exceeding a certain extentcan not be obtained from the gas heater device as a whole. On the otherhand, if the constricted portion 11 increases in diameter in order tosupply a large amount of water, the pressure difference produced betweenthe high pressure chamber and the low pressure chamber becomes verysmall and brings forth an inconvenience that a force is not obtainedenough to open the gas valve. To eliminate this inconvenience it hasheretofore been modified so that the diameter at the constricted portion11 can be varied by providing a piece 12 enabling to vary Venturi tubeadjacent to the constricted portion 11 through a screw rod 13 as shownin FIG. 9, said varying piece being displacable from outside by meansofa disc 14.

According to this structure the flow area of the constricted portion 11is variable, and so the flow area of said constricted portion 11 may beincreased for a small flow of water; conversely the flow area may bereduced for a large flow of water. However, the amount of water supplyof the gas water heater is generally very variable and the flow area ofthe constricted portion 11 must be adjusted from outside by a disc 14for each use of warm water, and this adjustment is very difficult.Sometimes, the diameter of constricted portion 11 is too much increasedand gas fails to fire, or the flow area is too much reduced and theamount of water flow is lowered to extreme extent. Thus thismanipulation has been so difficult.

Also in general housekeeping, the water supply to a gas water heater isbranched into other water supply appliances such as water faucets forsinks in the kitchen and for toilets, and the amount of water used inthese water supply appliances can vary the amount of water supply to thegas water heater. Consequently, in the case that the flow area ofVenturi portion is adjusted manually as in conventional gas waterheater, the amount of warm water supply necessarily varies depending onthe conditions of water use in other appliances even if the aperture ofthis outlet of warm water is constant. It sometimes occurs that thepressure difference of the hydraulic responding portion varies dependingon said variation of water supply and can not be noticed, or it canoccur that the pressure difference at Venturi portion is too muchreduced and the gas valve is shut carelessly, or the gun valve iscontrolled so that the flame formed in the gas combustion portionbecomes small and the condition of combustion is so unstable that it canbe put out by wind. For example, and in extreme cases the danger such asthe leakage of unburned gas can be considered seriously.

This invention is directed to the elimination of many defects inconventional type of gas water heaters, by providing a Venturi portionon the water passage leading to a heat exchanger, by inserting a controlelement automatically advancing or receding in conjunction with thevariation of water flow in the constricted portion of this Venturiportion to open or close a gas valve by the pressure difference betweenthe large diameter portion and the constricted portion of said Venturiportion, and by constructing the hydraulic responding portion so thatthe control element advances or recedes to vary the aperture area ofVenturi portion depending on the amount of water flow, the warm water inwide range from low temperatures to high temperatures is obtainable andthe combination in the gas combustion portion is very stable merely byadjusting the warm water outlet, and a highly reliable gas water heaterfor handy use is provided.

Another object of this invention is to obtain a gas water heater for usein wide range from small amount to large amount of water, that is, fromlow temperature to high temperature, by smoothening the flow of a largeamount of water making the aperture area of the constricted portion tobe large as a result of the retreat of the control element from theconstricted portion of Venturi portion in case the amount of water flowis large and the flow velocity of water is sufficiently high, or byincreasing the flow velocity of water at Venturi portion owing to thedecrease of the aperture area as the result of advancing of the controlelement to the constricted portion of Venturi portion in case the amountof water flow is small and the flow velocity is low, and by thusobtaining the pressure difference sufficient to open and close the gasvalve.

Another important object of this invention is to obtain warm water inall temperature range by merely adjusting the amount of warm water fromthe warm water outlet without any other operation as a result ofautomatic operation of the operator in connection with the variation ofwater flow, maintaining securely the combustion condition of thecombustion portion and eliminating careless closing of a gas valve orleakage of unburned gas even if the water supply pipe leading to the gaswater heater is branched to other water supply appliances and the amountof water supply to the gas water heater varies with the condition of useof those water supply appliances.

Another object of this invention is a good stabilization of gascombustion in the gas combustion portion by the assured displacement ofthe operator by a certain length which is initially determined by thecylindrical portion parallel on periphery of the control elementprojected into the constricted portion of Venturi portion because ofentry of a slight amount of water.

Further another object of this invention is to eliminate the occurrenceof eddy in Venturi portion by forming a certain length of taperedportion in the end of cylindrical portion of the control element in thetype wherein a control element is directly connected to a diaphragm,further smoothing the water flow and maintaining securely the pressuredifference produced in Venturi portion.

Further another object of this invention is to provide a gas waterheater of a type wherein a control element is provided independently-ofdiaphragm and prevents dropping of pressure difference or damage ofwater heating devices in simple construction by regulating water supplyat times of abnormal water pressure through the control element servingalso as a water governor.

Other various objects and advantages of this invention will beunderstood further clearly by the following detailed explanation withreference to the accompanying drawings.

FIG. 1 is a schematic view of a gas water heater showing incross-section a hydraulic corresponding portion of an embodiment of thisinvention;

FIGS. 2a and 2b are an explanatory views showing the action of anoperator in a hydraulic corresponding portion of FIG. 1;

FIG. 3 is a characteristic diagram of a gas valve;

FIG. 4 is a cross-section showing a hydraulic corresponding portion ofanother embodiment of this invention;

FIG. 5 is a cross-section of the essential part showing a modificationof FIG. 4;

FIG. 6 is a cross-section of a hydraulic corresponding portion of theother embodiment of this invention;

FIG. 7 is a cross-section of a hydraulic corresponding portion of FIG.6; and

FIGS. 8 and 9 are cross-sections of a hydraulic pressure correspondingportion in a conventional gas water heater.

Referring to FIGS. 1 to 3, one embodiment of a gas water heater of thisinvention will be explained.

In the drawings, 15 is a diaphragm operating chamber consisting of abase and a cover tightly integrated by rivets with the peripheralportion of a diaphragm 16 placed therebetween. Above said diaphragm 16is a low pressure chamber 20 and below said diaphragm is a high pressurechamber 21. 22 and 23 are a water supply inlet and a water feed outletcornmunicating with said high pressure chamber 21 and formed in the base18. 24 is a governor operating chamber provided between the water supplyinlet and the high pressure chamber and separated from this highpressure chamber 21 by a partition wall 26 having a water passage hole,and the portion opposing this partitioning wall 26 is usually closed bya plug body 27. 28 is a guide rod fixed to said plug body 27 at its oneend, and opposing to a water passage hole 25 of the partition wall 26 atthe other end. 29 is a governor slidably fixed onto the guide rod 28 andusually urged toward a water passage hole 25 by a spring 30 whoseprojected portion 31 projected from the end tits with clearance in thewater passage hole 25 of the partition wall 26 and contacts at its endportion with a lower receiving plate 32 of said diaphragm 16. When thewater supply pressure becomes abnormally high, said governor 29 isdisplaced upward in FIG. 1 by the upward bending of the diaphragm 16 aswell as by the action of the spring 30 so as to close the water passagehole 25 of the partition wall 26, thus preventing the damage andabnormal behavior of diaphragm 16 and other accessory machines andapparatuses. 33 is a Venturi portion formed in the connecting portion ofthe high pressure chamber 21 and the water outlet, and a constrictedportion 34 opposes the middle portion of said diaphragm l6 andcommunicates with the low pressure chamber 20 through a communicatingpassage 35. 36 consists of a cylindrical portion 37 with a periphery inparallel and tapered portion 38 formed on the end thereof. The base endof the cylindrical portion 37 is fixed to the middle of the lowerreceiving plate 32 in the diaphragm 16, and the other end portion of thecylindrical portion 37 and the tapered portion constitute a controlelement loosely fitted into the constricted portion 34 of said Venturiportion 33 and there usually exists a small clearance between thecylindrical portion 37 and the constricted portion 34.

39 shows a gas regulating portion. 40 is a valve case having a gassupply outlet 45 to a gas burner 42 and forming a valve seat 45' havinga gas opening 44 between said gas supply inlet 41 and gas supply outlet43, 45 is a gas valve always urged by a spring 46 so as to close a gaspassage hole 44, and 47 is an operating rod slidably passing throughsaid valve case 40 and the cover 19 of the diaphragm operating portionand engaging with an upper receiving plate 46 of the diaphragm 16 at oneend and with the gas valve 45 at the other end, respectively. 49 is aheat exchanger heated by the combustion heat of said gas burner 42, and50 is a warm water supply pipe mounted on said heat exchanger 49 andhaving a plurality of warm water faucets (not shown in the figure). Thiswarm water supply pipe 50 is connected to the water feed outlet 23 inthe base 18 forming a part of a diaphragm operating chamber 15, and thewater inlet 22 of the base 18 is connected to the water supply pipethrough a check valve, etc.

In a device according to one embodiment of this invention comprisingabove structures, if water is supplied to this high pressure chamber 21from the water supply inlet 22 of the diaphragm operating chamberthrough the governor 29 and then to the heat exchanger 49 throughVenturi portion 33 and the water feed outlet 23, the control element 36rushes into the constricted portion 34 of Venturi portion 33. Since theaperture area of this constricted portion 34 is small, the pressureacross this area falls as indicated by Bernoullis theorem, making thepressure lower in the low pressure chamber through communicating passage35. Accordingly, the diaphragm l6 bends upward because of the pressuredifference between the high pressure chamber 21 and the low pressurechamber 20 of the diaphragm operating chamber, thereby lifting thecontrol element 36 within the constricted portion 34.

The aforesaid bending condition of the diaphragm 16 is established whenthe pressure difference A between the high pressure chamber 21 and thelow pressure chamber 20 is balanced by the sum B of the elasticity ofspring 46 and the restoring force of the diaphragm itself. When thediaphragm 16 bends as described above causing the control element tomove so that the tapered portion 38 faces the constricted portion 34 ofVenturi portion 33 as shown in FIG. 2b, the aperture of said constrictedportion becomes larger and consequently the flow velocity of waterdecreases so that the pressure difference A between the high pressurechamber 21 and the low pressure chamber 20 becomes smaller.

And, when the aperture of the constricted portion reaches a certainvalue the diaphragm is held in equilibrium.

The operating rod 47 relieves the gas valve 45 of the gas passage hole44 of the valve seat 45 resisting the spring 46 by the bending of saiddiaphragm 16, thereby supplying gas to the gas burner. The combustion ofthe gas burner 42 heats the heat exchanger 49 and warm water is obtainedthrough the faucet of the warm water pipe 50.

When said warm water faucet is adjusted to vary the amount of warm watersupply, i.e., when the temperature of warm water is adjusted, the amountof water flow varies naturally.

In this case, the condition of opening of the gas valve 45 by thebending of diaphragm 16 is automatically maintained accurately since thecontrol element 36 automatically proceeds or recedes into or out of theVenturi portion corresponding to the amount of water flow.

For instance, when the flow changes from a small amount to a largeamount, the pressure at the constricted portion 34 of Venturi portion 33reduces to increase the pressure difference A because of the increase offlow velocity of the water, thereby bending the diaphragm 16 moreupward. Because of this bending of the diaphragm 16 the smaller portionof tapered portion 38 of the control element 36 faces the constrictedportion 34 and when the pressure difference A is balanced by the sum ofthe restoring force of diaphragm l6 and the elastic force of spring 46,the bending action of the diaphragm 16 is stabilized.

In such a case as temperature control by regulating the amount of water,the diaphragm 16 does not reach the stabilized bending position at onetime. When the increase or decrease of the amount of flow changes thepressure at the constricted portion 34 of Venturi portion 33 to producethe pressure difference between the high pressure chamber 21 and the lowpressure chamber 20, the diaphragm 16 operates by that pressuredifference, thereby causing the control element 36 to move in theconstricted portion 34. Accordingly, the pressure in the constrictedportion 34 varies in a smaller range than the previous value, andconsequently the diaphragm 16 behaves as if vibrating within this rangeand finally is stabilized in a certain bent condition.

The gas valve 45 must always be opened sufficiently independently of theamount of water.

For this purpose, a means is provided how to fit the control element 36to the constricted portion 34 at the time of interruption of water flowand said require-- ments are satisfied. If, as shown in FIG. 2a, thecylindrical portion 37 of the control element 36 is projected into theconstricted portion 34 as long as 1 during interruption of water supply,the aperture of the constricted portion 34 does not vary so long as saidcylindrical portion faces the constricted portion; consequently, even ifa small amount of water flows, the diaphragm l6 bends more as much asthe control element 36 moves more than 1. Assume that the whole controlelement is tapered, the aperture of the constricted portion changes evenby a slight action of the control element and a great magnitude ofmovement of the diaphragm can not be obtained by a small amount ofwater. Consequently, if the cylindrical portion 37 of the controlelement 36 is intruded by the length 1 into the constricted portion 34of Venturi portion 33 as in this invention, the diaphragm l6 bends atleast and more than 1 and the gas valve 45 can be relievedinstantaneously by this variant value 1.

FIG. 3 shows the relation of the water amount Q to the aperture G;according to this diagram, in the case of this invention the cylindricalportion 37 of the operator 36 is projected into the constricted portion34 of Venturi portion 33 by a certain value of length and acharacteristic curve C is obtained and a small amount of watercompletely opens the gas valve 45 instantaneously. In the case that thewhole control element is tapered, the gas valve is not completely openedunless the water amount exceeds a certain value as shown by D, and itwill be understood the valve is gradually opened until the certain valueis reached.

As well known, in the gas combustion equipment, if the amount of gassupply is small compared with the combustion capacity, the tire will beeasily put out by wind, etc. and stable combustion is not obtained.

In FIG. 3, let G be the minimum aperture of a gas valve required for gassupply necessary to complete combustion, then it will be understood thatthe gas valve aperture for complete combustion is obtained at a verysmall amount of water Q for the characteristic curve 0 according to thisinvention and that a large amount of water is necessary for thecharacteristic curve D of the whole tapered control element.

Accordingly, the combustion of gas is very stable when the amount ofwater flow is small for this invention; it is not only of highreliability but also able to widen the variation of water amount, i.e.,the adjustable range of temperatures of warm water.

In FIGS. 1 and 2 showing one embodiment of this invention, the controlelement 36 which varies the aperture of the constricted portion 34 ofVenturi portion 33 may have a wholly cylindrical form without a taperedportion 38 at its end and this form of control element works any way. Inthis case, the aperture of the constricted portion 34 is established bythe fact that how far the end of the cylindrical portion 37 of operator36 is distant from the constricted portion 34.

In this case, however, the water passing between the constricted portion34 and the cylindrical portion 37 generates eddies because the end faceof the cylindrical portion 37 is a large flat plane; it is apparenttherefore that a difficulty will be caused in the reduction of thepressure at the constricted portion 34.

If the tapered portion 38 is formed on the cylindrical portion 37, it iseffective in smoothing the flow of water passing through the constrictedportion 34 and there is no occurrence of eddies, assuring the pressuredifference.

To express briefly the feature of the device of one embodiment accordingto this invention, it can change the temperature of warm water merely bythe adjustment of water amount from the warm water outlet and beoperated very easily; the water supply passage leading to this device isbranched into other water supply appliances, and even if the watersupply to this device varies depending on the amount of water used inthese other water supply appliances, it does not occur that the gasvalve is closed inadvertently or that unburned gas leaks because ofextinguishment of gas combustion, thus exhibiting an excellency in termsof safety.

To explain another embodiment of the hydraulic responding portion, FIG.4 is different from previous embodiments and shows an example wherein adiaphragm and a control element are not directly connected but existindependently of each other.

In FIG. 4, the high pressure chamber 21 of a diaphragm operating chamberserves also as a middle part of a water supply passage and forms aVenturi portion 51 between the high pressure chamber 21 and a wateroutlet 23. The constricted portion 52 of this Venturi portion 51communicates with the low pressure chamber of the diaphragm operatingchamber 15 through a communicating passage 53. Said Venturi portion 51has an opening closed by a plug body 54 at one axial end, and the baseend of a guiding rod 55 facing the central portion of the Venturiportion 51 is fixed to said plug body 54, the end of said guiding rod 55reaching near the constricted portion 52. 56 is a control element fittedloosely in Venturi portion 51 in the condition that it is mountedslidably onto the guiding rod 55, and has a tapered portion 57 on itsone side and a flange 58 projected outward on the other end. 59 is aspring urging the control element 56 to protrude into the constrictedportion. 60 is a stopper which determines the position of the operator56. When water does not flow, the control element 52 contacts with theend of this stopper 60 and takes its position where the portion oflargest diameter opposes to the constricted portion 52.

In the above device, the water flowing in from the water supply inlet 22reaches the diaphragm operating chamber 15 through a governor 29 and isthen sent to a heat exchanger through Venturi portion 51 and a wateroutlet 23. In this case, a part of the water passing through Venturiportion 51 collides against the flange 58 of the control element 56 andthe element 56 resists the spring 59 by this water pressure so that thetapered portion 57 slides in such a direction as to come out of theconstricted portion 52. And this sliding stops at a point where therepulsive force of the spring 59 and the hydraulic pressure acting onthe flange 58 acting in opposing directions to each other are balanced,thereby stabilizing the control element 56. Consequently, the apertureof constricted portion 52 of Venturi portion 51 is automatically set tothe optimum value corresponding to the amount of water at that time andcan securely cause the pressure drop of the constricted portion 52.Because of this pressure drop in the constricted portion 52, the lowpressure chamber 20 of the diaphragm operating chamber 15 becomes low inpressure through the communicating passage 53, causing the diaphragm 16to bend upward owing to the pressure difference between the low pressurechamber 20 and the high pressure chamber 21, opening a gas valve with anoperating rod 47. In case the amount of water flow varies by adjustingthe warm water outlet, the hydraulic pressure acting on the flange 58 ofthe operator 56 and the repulsive force of the spring 59 becomeunbalanced and the control element 56 accordingly moves to a positionwhere said two forces are balanced, securing the aperture of theconstricted portion 52 corresponding to the amount of water at thattime. For instance, if the warm water amount is controlled in order toobtain water of a high temperature, the consequent decrease of theamount of water flow reduces the hydraulic pressure acting on the flangeS8 of the operator 56, and the repulsive force of the spring 59 at thattime reduces said hydraulic pressure. Consequently, it follows that theoperator 56 moves so that its tapered portion 57 protrudes into theconstricted portion 52; and when the operator stops to move afterbalancing again the repulsive force of the spring against the hydraulicpressure, the tapered portion of larger diameter faces the inside of theconstricted portion. As a result, the aperture of this constrictedportion is smaller than it was before and the flow velocity of water inthe constricted portion is kept high and a sufficient pressure drop isobtained regardless of the decrease of the amount of water.

The most important matter in the above device is the mutual relation offorces comprising the hydraulic pressure acting on the flange 58 of theoperator 56 and the repulsive force of spring acting in the oppositedirection. If the repulsive force of the spring 59 is too large, theincrease of the amount of water flow, and therefore, a larger hydraulicpressure acting on the flange 58 of the control element 56 does notshift said element, so that the aperture of the constricted portion 52becomes small relative to the amount of water flow, and the flowresistance of water will apparently increase remarkably. On the otherhand, if the repulsive force of the spring 59 is too small, thehydraulic pressure acting on the flange 58 becomes larger than therepulsive force of the spring 59 even when the amount of water flow isvery small so that the control element 56 moves in such a direction asto come out of engagement with the constricted portion 52, andconsequently the aperture 52 is large for a small amount of water andsufficient pressure will not be obtained. Therefore, when the pressureacting area of the flange 58 and the repulsive force of the spring 59are selected, the range of variation of water flow and the range ofvariation of aperture of the constricted portion 52 must be consideredin connection with this; if the repulsive force of the spring is made tobe adjustable, it is very advantageous in adjusting minute balance.

FIG. shows an example of adjusting the repulsive force of the spring 59wherein a threaded portion 61 is formed on the guiding rod 55, thisthreaded portion 61 is screwed into the plug body 54 and on one end ofthe protruded threaded portion is mounted a disc 62, one end of spring59 is received by a spring receiver 63 provided on the way to theguiding rod 55 and the other end of spring 59 is arranged to be receivedby the end face of the flange 58 of the control element 56.

In the above structure, if the guiding rod 55 is rotated through thedisc 62 to advance, the spring 59 is compressed and its repulsive forceincreases. If the guiding rod retreats, the spring repulsive forcedecreases. As a result, the balance of the repulsive force of spring 59against the hydraulic pressure on the flange 58 of the control element56 can be kept optimum in connection with the range of variation of theamount of water flow and the range of variation of aperture of theconstricted portion 52. In addition, the fluctuation of elasticity ofthe spring 59 and the fluctuation of size of the control element 56 canbe absorbed by adjusting the disc 62.

It goes without saying that said disc 62 is all for adjusting therepulsive force of the spring 59 and essentially different from such aone as a conventional type of disc 14 for moving a control elementitself. When the amount of warm water supply or the temperature of warmwater is changed, the control element 56 of FIG. 5 of course movesautomatically without any manipulation of the disc 62.

FIGS. 6 and 7 show examples in which a control element serves also as agovernor. A Venturi portion 64 is formed between a water supply inlet 22and a water outlet 23, and a large diameter portion 65 is connected tothe high pressure chamber 21 of a diaphragm operating chamber through acommunicating passage 66, and a constricted portion 67 is connected tothe low pressure chamber through a communicating passage 68, and a valveseat 69 is formed in the communicating passage 68 of the constrictedportion 67 with the water outlet 23, and a control element 70 is formedby directing outward a flange having a hydraulic pressure acting portion71a and an opening or closing valve portion 71b.

In the above device, the fundamental operation is the same as the deviceof FIG. 4 in that the control element 70 functions depending on thevariation of the amount of water flow and the aperture of theconstricted portion 67 is set automatically to a value suitable to theamount of water to obtain a secure bent condition of the diaphragm 16.But in the device shown in FIGS. 6 and 7, a high hydraulic pressure actson the hydraulic pressure acting portion 71a of the flange 71 of thecontrol element 70 when the hydraulic pressure becomes abnormally high,thereby advancing the control element 70 extremely forward. In thiscase, the valve portion 71b of the flange 71 approaches the valve seat69 and regulates the flow of water to cause the hydraulic pressure tofall. Consequently, this device is very effective in use in the areawhere the water supply pressure is not stable. This device does notrequire a particular cover and can be built mechanically simple, and atthe same time an extreme deformation of diaphragm, etc. because ofextraordinary hydraulic pressure of the damage of copper tubes, etc.mounted on the heat exchanger portion locally low in strength can beprevented.

As above, embodiments of this invention were explained, but it isapparent that this invention can be variously modified without departurefrom the spirit of this invention and within the scope of thisinvention.

We claim:

1. A valve assembly for controlling the supply of water and gas to theheat exchanger portion of a gas water heater, comprising:

a diaphragm operating chamber divided into a high pressure chamberportion and a low pressure chamber portion;

a diaphragm disposed in said diaphragm operating chamber for separatingsaid high pressure chamber portion from said low pressure chamberportion;

gas control means connected to said diaphragm for controlling the supplyof gas to said heat exchanger portion;

governor means connected to said diaphragm for controlling the rate offlow of water into said valve assembly from a water supply inlet;

water flow path means communicating said high pressure chamber portionwith said heat exchanger portion, said flow path means comprising aVenturi portion having a constricted region, a first passagewayconnecting the input of said Venturi portion with said high pressurechamber portion, and a second passageway connecting the output of saidVenturi portion with said heat exchanger portion; further passageway,having a smaller cross-sectional area than said first passageway,connecting said Venturi portion with said low pressure chamber portion;

a control member having a tapered portion at one end which protrudesinto the constricted region of said Venturi portion and an opposite endportion acted on by the hydraulic pressure of water flowing through saidwater flow path means;

means mounting said control member in said valve assembly independentlyof said diaphragm to be freely movable into and out of the constrictedregion of said Venturi portion; and

biasing means resiliently urging said control member normally in adirection opposite to the direction of and against the pressure of theflow of water in said water flow path means.

2. A valve assembly according to claim 1, further comprising adjustingmeans for adjusting the biasing force of said biasing means.

3. A gas water heater as described in claim 1 characterized by forming avalve seat on water supply passage adjacent Venturi portion andintegrating the valve portion cooperating with said valve seat and saidcontrol element opposing thereto.

# l t i i

1. A valve assembly for controlling the supply of water and gas to theheat exchanger portion of a gas water heater, comprising: a diaphragmoperating chamber divided into a high pressure chamber portion and a lowpressure chamber portion; a diaphragm disposed in said diaphragmoperating chamber for separating said high pressure chamber portion fromsaid low pressure chamber portion; gas control means connected to saiddiaphragm for controlling the supply of gas to said heat exchangerportion; governor means connected to said diaphragm for controlling therate of flow of water into said valve assembly from a water supplyinlet; water flow path means communicating said high pressure chamberportion with said heat exchanger portion, said flow path meanscomprising a Venturi portion having a constricted region, a firstpassageway connecting the input of said Venturi portion with said highpressure chamber portion, and a second passageway connecting the outputof said Venturi portion with said heat exchanger portion; a furtherpassageway, having a smaller cross-sectional area than said firstpassageway, connecting said Venturi portion with said low pressurechamber portion; a control member having a tapered portion at one endwhich protrudes into the constricted region of said Venturi portion andan opposite end portion acted on by the hydraulic pressure of waterflowing through said water flow path means; means mounting said controlmember in said valve assembly independently of said diaphragm to befreely movable into and out of the constricted region of said Venturiportion; and biasing means resiliently urging said control membernormally in a direction opposite to the direction of and against thepressure of the flow of water in said water flow path means.
 2. A valveassembly according to claim 1, further comprising adjusting means foradjusting the biasing force of said biasing means.
 3. A gas water heateras described in claim 1 characterized by forming a valve seat on watersupply passage adjacent Venturi portion and integrating the valveportion cooperating with said valve seat and said control elementopposing thereto.